tested at 5.5.1.0.1, compatibility with GlobalSCAPE sftp server. partner server's key exchange fails validation. first we saw "Public key is not in the default format, attempting parse with other supported formats" in a debug SFTP-client log, then "The host key signature is invalid".

we found that once the GlobalSCAPE server was configured to use the hmac-md5-96 MAC algorithm, the key exchange was successful.